Seasonal incidence of rice yellow stem borer, Scirpophaga incertulas (Walker) on different accessions in rice agro-ecosystem

Studies on population dynamics of yellow stem borer on different rice varieties revealed that the dead heart formation was observed from the 2^nd week of August and peak deadheart formation was observed during 4^th week of September in PS-15 (30.3%) followed by PR-113 (26.7%) and was minimum in HKR-4 (14.6%). The white ear head formation started from the 1^st week of September and attained its peak during 2^nd week of November with maximum white ears in NDR-359 (44.9%) followed by PR-113 (44.3%) and minimum in variety PS-5 (27%). White earhead symptom and weather parameters, showed that varieties, PR-113, HKR-47 and PS-15 exhibited significant negative correlation with maximum temperature. Significant negative correlation values -0.962, -0.927, -0.903, -0.931, -0.940 and -0.931 were recorded in varieties, PR-113, HKR-47, PS-4, NDR-359, Sarju-52 and PS-21, respectively with minimum temperature. Varieties PR-113, NDR-359, and Sarju-52 showed significant negative correlation with minimum relative humidity.